Aqua hot expansion tank

[John Moore]

I have an 06 Monterey beaver, after running my Hydro hot for a period of time I notice my expansion tank level doesn't change from the cold fill line to the hot line. I have checked the clear hose from the pressure tank to the expansion tank and blew through it and got bubbles in the expansion tank so I know it's clear, I also replaced the pressure Cap( 13lb )  The old one was original and it had rotted and cracked and the rubber was almost gone. I did have it serviced last year but obviously not from a good service technician. I did add 2 gallons of distilled water  to bring the level back up to the top of the cap. I plan on flushing the system soon and have the hydro hot annual maintenance done. Any ideas why my expansion tank does not change levels. I do not see any leaks anywhere. Thanks for your help.  I have read a lot of Orman Claxton replies but nothing in that address this issue.

[Steve Huber Co-Admin]

John,
If you blew through the hose and saw bubbles in the expansion tank, maybe check for an obstruction in the orfice at the main tank.
Steve

[Karl Welhart]

John,

Assuming you disconnected the hose between the expansion tank and the main fill neck (below radiator cap)?  If so, does the expansion tank drain out?  Understanding that you added distilled water to the main coolant tank and did not change the expansion tank level, would lead me to believe the main coolant tank is below full and the expansion tank is plugged is some way that will let you blow bubbles but coolant is not going in/out of expansion tank.

I would recheck the main tank coolant level (system should be cold) and refill if necessary.  Remove the expansion tank, clean the inside to remove any permenant level lines, replace hose with new clear plastic w/clamps and fill to cold line with coolant mixture.  Run in diesel mode a couple cycles and see what happens.

Good luck,

[John Moore]

 OK thanks for the info I will try that

[John Moore]

Does the clear hose from pressure cap to expansion tank need to be primed with fluid or is air in the line ok.?

[Karl Welhart]

John,

Air in the line is OK.  No need to prime that line.  Just fill the main tank, replace cap, fill the expansion tank to cold line and run the system in diesel mode.

[John Moore]

Hi Ken, I did as you say and Aqua hot works fine, both water and furnace. Is it a problem if expansion tank does not fill at all after a couple of heating cycles, pressure tank is full and no leaks that I can see?

[Frank Bergamo]

John, don't know if two cycles with little or no demand on systems is enough to open 13 PSI cap. Some have used 7 PSI cap to reduce pressure on system. Keep an eye on system under high demand and you should be able to diagnose if system is operating properly. Hope this helps.

[Michael Rump]

John,
Another place you might check for leaks is around the base of the filler cap on the tank. The solder will let go over time and the fluid will seep down around the tank. Please be careful when checking under pressure.

[Karl Welhart]

If the system's main tank is full and the cap is operating properly, you should see the level in the expansion tank go up and down.  If the main tank has air, you may not see any movement in the expansion tank.  Keep checking the main tank and keep filling the expansion tank until the system clears itself of air.

[John Moore]

 Thanks to all, I had too much air in the system but kept filling and it worked itself out, it did take several cycles, also where my clear hose exit underneath the pressure cap  it goes below two large hoses and they were patching in a little bit. Also I have heard several people mentioned the solder is often the problem which I will keep an eye in the future. Thanks again, John

[David T. Richelderfer]

It was noted in an earlier post on this thread that the solder on the collar between the pressure cap and Aquahot tank will decay over time and may leak coolant or fully release the collar from the tank.  This happened to my Aquahot and Mike Flowerday used JB Weld epoxy to glue it back on.  It's been holding for three years or so, but I have not had to touch the pressure cap either.  Logically, the more times the pressure cap is removed, the more likely the solder will fail.

[Frank Bergamo]

As David noted, the filler neck can become disconnected from boiler tank. Here is a link that permanently fixes that problem.  http://beaveramb.org/forum/index.php/topic,3057.msg22866/topicseen.html#msg22866 Hope this helps for those having this problem. It is a fairly straight up fix that most can do with limited mechanical ability. Sure beats the cost of replacing unit with a new one.